Vaporizer



F. J. r-:lcHELMAN ETAL 2,968,474

VAPORIZER Jan. 17, 1961 3 Sheets-Sheet 1L Filed Sept. 25, 1957 Jan. 17,1961 F. J. ElcHELMAN ErAL 2,968,474

` vAPoRIzER Filed sept. 25, 1957 Y s sheets-sheet 2 Jan. 17, 1961 F. J.EICHELMAN ETAL 2,968,474

. VAPORIZER Filed Sept. 25, 1957 3 Sheets-Sheet 3 'QQ f J0 VAPORIZERFrancis .1. Echelman, Brookeld, and Norman C.

`Graunke, Lyons, Ill., assignors to Chemetron Corporation, Chicago,Ill., a corporation of Delaware Filed Sept. 25, 1957, Ser. No. 686,085

9 Claims. (Cl. 261-46) This invention relates in general to apparatusfor vaporizing liquids and more particularly to apparatus forcontrolling and regulating liquid-gas contact in the administration ofgaseous iiuids, vaporized liquids and the like.

Heretofore, vaporization of liquids, such as ether, for example, hasbeen achieved by employing multi-valved, multi-chambered controlmechanisms attached to oversized liquid containing vessels in which aretelescoped perforated vessels for supporting evaporator wicks,foraminous materials or bulky contact plates generally of copper. Suchdevices are expensive, unwieldy, and do t not lend themselves to ready,simple, and elicient operation.

Applicants have developed a novel, inexpensive, and compact device whichachieves maximum vaporization simply, eiciently, and positively. Thedevice essentially comprises a control unit embodying relatively movablemembers which are provided with passages and grooves. The control unitis associated with a container for liquid which contains a simple,highly eilicient gaseous fluid diffusing apparatus. A knob on thecontrol unit provides selective movement of the passages and grooves ofthe relatively movable members into various positions of registerenabling a user to rapidly and positively perform three fundamentaloperations with the device; rst, passing all gaseous fluid through theliquid in the container; second, by-passing selective portions of thegaseous fluid so that no contact is made with the liquid in thecontainer while simultaneously passing the remainder of gaseous uid intoand through the liquid; and third, bypassing all of the gaseous iiuid sothat it makes no contact with the liquid in the container.

As an added feature, applicants have provided novel means in the controlunit for relieving automatically any excessive pressures developed fromvaporization of liquid in the container, thus eliminating danger ofpressure caused explosions, especially when the device is employed inconnection with highly volatile agents such as ether.

1t is, therefore, an object of this invention to provide a vaporizingdevice of compact, inexpensive construction capable of ready and simpleoperation.

It is another object of this invention to provide a vaporizing devicehaving a minimum of moving parts which is capable, by selectiveoperation, of etiiciently and positively passing all incoming gaseousfluids through a vaporizable liquid, or by-passing portions or all ofthe gaseous fluids so that no contact is made with the liquid.

.lt is still another object of this invention to provide a vaporizingdevice capable of selectively combining optimum amounts of gaseous fluidand vaporized liquid for delivery to a point of use.

Another, and perhaps less obvious, but none the less important, objectof this invention is to provide a vaporizing device capable of eicientlyand safely relieving any excessive pressures resulting from vaporizationof liquid used in connection with the device.

These objects and additional advantages and features atent O of thisinvention will become more readily apparent as the following descriptionproceeds, taken in conjunction with the accompanying drawings wherein:

Fig. l is an elevational view of an embodiment of the invention.

Fig. 2 is a fragmentary sectional view illustrating the funnel andfilling passage of the apparatus of Fig. 1.

Fig. 3 is a fragmentary sectional View of the bleed passage of thedevice of Fig. l.

Fig. 4 is a sectional view along line 4-4 of Fig. 1.

Fig. 5 is a top plan view of the apparatus illustrated in Fig. 4 withthe plate assembly and control knob removed.

Fig. 6 is a top plan View of the plate assembly and control knobillustrated in Fig. 4.

Fig. 7 is an exploded view partly in section of the valve arrangement inthe control head unit with single headed arrows illustrating the passingof a portion of gaseous iiuid through the liquid and double headedarrows illustrating the by-passing of another portion of gaseous Huid.

Fig. 8 is a top plan view similar to Fig. 5 illustrating the relativepositions of the grooves and passages during the operation shown in Fig.7.

Fig. 9 is a top plan View similar to Fig. 6 illustrating the position ofthe control knob during the operation shown in Fig. 7.

Fig, 10 is an exploded view partly in section of the valve arrangementin the control head unit illustrating with arrows the ilow of allgaseous fluid through the liquid.

Fig. l1 is a top plan view similar to Fig. 8 illustrating the relativeposition of the grooves and passages during the operation shown in Fig.10.

Fig. l2 is a top plan view similar to Fig. 9 illustrating the positionof the control knob during the operation shown in Fig. 10.

Fig. 13 is a sectional view along line 13-13 in Fig. 4.

For convenience of illustration and description, a cornmercialapplication of applicants invention in the form` of a vaporizer foranesthetic purposes has been illustrated and will be described below. Itwill be understood, however, that the principles and apparatus involvedmay be related to other vaporizer devices for other purposes withoutdeparting from the spirit of the invention.

Referring now in greater detail to the drawings and more particularly toFigs. l and 4, the numeral 14 designates a container which preferablytakes the form of a cylindrical jar and which may be calibrated ifdesired. The container 14 may be formed of glass, or other material,which is relatively chemically inert to such agents as ether andtrichloroethylene, and yet is of suicient strength to withstand normalpressures developed in the vapor'ization of such volatile substances.

The container 14 preferably is provided with a collar 15 having asealing member 16 interposed between it and the container 14. The collar15, in addition, is provided with an annular groove 1'7 adapted toreceive a sealing gasket 18. The collar 17 preferably is reduced at oneend andtprovided with an externally threaded portion 19.

A control head unit designated by numeral 20 and preferably providedwith an internally threaded flange 21, is adapted to engage thecorrespondingly externally threaded portion 19 of collar 15. The edge ofthe ange 21 is provided with an integral annular ring 23, whichcooperates with sealing gasket 1S to provide a positive gas seal betweencontainer 14 and control head unit 29 when the latter are in engagement.

Referring additionally to Figs. 1 and 4, the preferred embodiment ofcontrol head unit 20 is provided with a housing 24 forming a chamber 25,one Wall of which is formed by a detachable closure plate 26. Theclosure plate 26 may be secured to housing 24 by screws 27. A sealinggasket 28 is provided between housing 24 and closure plate 26 to seal ochamber 25 from the atmosphere.

The flanged base 30 of housing 24 is provided with a passage 31 (seeFig. 2) communicating with the internal of container 14. A funnel 32,having communicating passage 33 and stopper 34, is secured to housing 24for introduction of liquid into container 14 when the control head 20 isin place.

The base 30 of housing 24, in addition, is provided with a bleed passage35 (see Fig. 3) also communicating with the internal of container 14.Bleed passage 35 permits gaseous fluid and vaporized liquid to escapefrom container 14 when liquid is introduced into the latter throughfunnel 32. A knurled screw 36 provided with a gasket 37 releasablycloses the passage 35 and seals it from the atmosphere when the deviceis not being filled.

Referring now to Figs. 4, 7, and 10, the base 30 of housing 24preferably is provided with aligned passages 40 and 41 each of whichcommunicates with an inlet member 42 and a preferably barbed outlet stem43, respectively. Inlet member 42 is adapted to receive a conduit orhose, not shown, for connection to a source of gaseous iluid underpressure, also not shown. Similarly, stem 43 is adapted to be connectedto a conduit orhose for carrying off gaseous fluid or vaporized liquidto a point of use.

The base 30 of housing 24 is further provided with spaced throughpassages 44 and 45 transverse to and intersecting with passages 40 and41, respectively, each communicating with chamber 25. Through passage 44(see Figs. 7 and l0) opens into an arcuate groove 46 in the base 30.Another through passage 47 and a preferably axial through passage 48also are provided in the base 30 and communicate with the internal ofcontainer 1'4 and chamber 25. The Ibase 30 is still further providedwith another passage 49 opening into cihamber 25 and intersecting atransverse passage 50, the latter communicating with passage 48.

Threadedly connected to the base 30 and forming an extension of axialpassage 48 is a tubular member 60 through which gaseous liuids enteringinlet member 42 may be directed into the container 14 as will bedescribed below. The tubular member 60 is provided with a hexagonalsurface 61 allowing said member to be more easily engaged or disengagedfrom the base 30. A gasket 62 is provided between surface 61 and base 30to insure a gas seal between the internal of container 14 and the axialpassage 48. The lower end of the tubular member 60 preferably isprovided with external threads 63 for engagement with a diffuser body 64having an internally threaded tubular neck 65 and a substantially plainsurfaced base 66.

The neck 65 of the diffuser body 64 receives one or more washer-likebodies such as 67, 68, and 69, and is provided with diametral outlets70, 71, and 72 at the relatively movable contacting surfaces of thewasherlike bodies. For a more complete description of this preferreddiffuser body 64 and its operation, reference may be had to co-pendingapplication Serial No. 608,873, filed September l0, 1956, and now PatentNo. 2,902,269, issued September 1, 1959, of which this application is acontinuation-in-part.

Returning agai-n to control head unit 20, a valve member or spool 80preferably is centrally positioned within chamber 25. The valve member80 is provided with a stub shaft 81 adapted to be received in axialpassage 48. Valve member 80 is preferably made of a lightweightchemically inert substance such as Teflon. This preferred material doesnot require lubrication and will not bind when valve member 80 is movedrelative to the base 30.

Referring to Fig. 13, valve member 80 preferably is provided with spacedthrough passages 82 and 83, passage 82 being reduced to act as ametering device for incoming gaseous fluid. Passage 83 opens into anarcuate groove 84 in surface 85 of valve member 80. In addition, surface85 is provided with an arcuate groove 86 having a comet tail-liketapering extension 87 of progressively varying depth. The function ofgrooves 84 and 86 will be treated in greater detail when the operationof the device is later discussed.

The upper surface 88 (see Fig. 4) of valve member 80 preferably isprovided with a slotted stub shaft 89. A keyed stem or shaft member 90extends through closure plate 26 and engages the slot of stub shaft 8.9.A compression spring 91 is interposed between the surface 88 and closureplate 26 about shaft 90. A flange 92 on stem 90 depresses spring 91against the surface 88 of the valve member 80 when closure plate 26 issecured to housing 24. The bias thus exerted by spring 91 on valvemember 80 is sufficient to provide a substantial gas seal betweensurface 85 and the base 30. On the other hand, the bias exerted byspring 91 is such that in the event excessive pressures develop in thecontainer 14, the valve member 80 will be raised from its position inrelation to base thereby permitting expansion into chamber 25 of thegaseous fluid and vaporized liquid causing such pressures to exit viapassages 44 and 40 and 45 and 41. This relief valve function of valvememlber 80 and spring 91 provides an important safety factor in theoperation of the vaporizing device in that it prevents fracturing of thecontainer 14 in the event that excessive pressures develop.

The rotational movement of valve relative to base 30 of housing 24 iscontrolled by a knob 93 secured to stem 90. The knob 93 is provided witha pointer 94 which in cooperation with a suitably marked plate 95,indicates on and olf positions of the device, in addition to indicatingintermediate positions of control for gaseous tluid-vaporized liquidmixtures.

A stop pin, not shown, preferably depending from closure plate 26 isadapted to engage a recessed portion, also not shown, in the edge offlange 92 permitting the knob 93 to move the valve member 80 only topositions from full on to full olf.

Operation Having thus described the construction of the illustratedvaporizing device, a discussion of its operation follows. Applicantsvaporizer is susceptible of many uses. It has, for example, been foundto present an extremely practical apparatus for humidifying inhalautgases as well as for vaporizing liquids more volatile than water, suchas ethers and other volatile organic solvents. In regard to the lastmentioned use, the apparatus has provided novel means for quickly andselectively controlling the administration of an anesthetic mixtureincluding oxygen or pure gaseous fluid such as oxygen, best suited toall circumstances attending anesthesia and post-anesthesia conditions ofsurgical patients.

Referring to Figs. 10, 1l, and l2, when it is desired to direct all of agaseous fluid, such as oxygen, into and through a liquid, such as etherin container 14, to obtain maximum vaporization, the control knob 93 andpointer 94 are turned to the full on position illustrated in Fig. 12. Inthis position (see Figs. 10 and ll) arcuate groove 86 in surface 85 ofvalve member 80 is in register with through passages 44 and 49, andarcuate groove 84 is partly in register with through passage 45, and infull register with passage 47 in the base 30 of housing 24. As clearlyindicated by arrows, oxygen, for example, enters inlet member 42, flowsthrough intersecting passages 40 and 44 in base 30, into groove 86 invalve member 80 from where it is directed through intersecting passages49 and 50 into axial passage 48 in base 30. The gas then ows throughtubular member 60 to the diffuser body 64 (see Fig. 4) from whence itissues into the liquid in container 14. After the gas is diffusedthrough the liquid in container 14, vaporized liquid carried in thegaseous medium flows through passage 47 in base 30, into arcuate groove84 in valve member 80 from whence it is directed into and throughintersecting passages 45 and 41 to outlet stem 43. Chamber 25 is filledwith vaporized liquid during this operation by way of arcuate groove 84and through passage 83 in valve member 80. This creates a balancedpressure condition in chamber 25 which aids the flow of vaporized liquidfrom the control head unit 20, but does not interfere with incominggaseous fluid. It is obvious from the foregoing that this easilycontrolled operation of the device is employed to rapidly place apatient under the iniluence of anesthetics preparatory to surgery.

Referring now to Figs. 7, S, and 9, an intermediate position of thevalve member 80 with relation to the passages in base 30 of housing 24is illustrated. In this position, groove 46 in base 30 is in registerwith passage 82 in valve member 80. Through passage 44 in base 30 is inregister with a portion only of tapering extension 87 of arcuate groove86 in valve member 80, and arcuate groove S6 in turn is in register withthrough passage 49 in base 36. In addition, through passage 83 andarcuate groove 84 in valve member S0 are in register with throughpassages 47 and 45, respectively, in base 30 of housing 24. As indicatedby the single and double headed arrows, incoming gaseous iluid, such asoxygen, ilows through intersecting passages 4t) and 44 in base 30. Aportion of the oxygen indicated by the double headed arrows, flowsthrough groove 46 in base 30 and thence through passage 82 in valvemember S0 into chamber 25. This part of the oxygen thus by-passes theliquid in container 14. The remainder of the incoming oxygen follows thepath of the single headed arrows and is directed by tapered extension 37of arcuate groove 86 in valve member 80 through groove 86 intointersecting passages 49 and 50, the communicating axial passage 48 inbase 30 and tubular member 60 into the container 14. This portion of theoxygen is diffused into and through liquid in container 14 in the samemanner as explained in the next preceding operation of the device inconnection with full vaporization of the anesthetic by the gaseousmedium. The vaporized liquid carried in the gaseous medium leavescontainer 14 through passage 47 in base 30 and ilows into arcuate groove84 in valve member 80 Where it is combined with by-passed oxygen fromchamber 25 entering groove 84 through passage 83 in valve member 80. Thegaseous fluid-vaporized liquid mixture then llows through intersectingpassages 45 and 41 in base 30, through outlet stem 43 from where it isconducted to a point of use. It will be noted that the control knob 93can be moved through a considerable intermediate range and that,therefore, the degree of register of the various passages and groovescan be controlled to give the desired gaseous lluid-vaporized liquidmixture in accordance with the need of the patient. This quick andefficient control makes it possible for the operator to bring thepatient rapidly to the optimum depth of anesthesia and to maintain suchdepth. When anesthesia is no longer required, pure gaseous fluid may beby-passed to the patient in the manner to be described.

Referring to Figs. 4, 5, and 6, when it is desired to by-pass liquid incontainer 14 and to administer gaseous fluid only to a patient, thecontrol knob 93 and pointer 94 are turned to the off position asillustrated in Fig. 6. In this position, through passages 82 and 83 invalve member 80 are in register with passages 44 and 45, respectively,in base 30 of housing 24. Gaseous fluid, such as oxygen, under pressure,enters inlet member 42, flows through intersecting passages 4t) and 44in base 30, thence through passage 82 in valve member 80 into chamber25. The gas then flows through chamber 25 into passage 83 in valvemember 80, through passages 45 and 41 in base 30 of housing 24, and outstem 43 from which point it is directed by a suitable conduit to a pointof use. This by-pass operation of the device is particularly valuableduring surgery, for example, where it is observed that anesthesia is toodeep and the respiration of the patient is dropping off. Pure gaseousfluid, such as oxygen, may be quickly directed to the patient by sirnplyturning the control knob 93 to the oil position. The immediate anddesired result will be increased respiration thus partially overcomingthe effects of the anesthetic. In addition, this by-pass operation ofthe device may be employed as a post-operative technique for bringing apatient wholly or partly back to consciousness. Such complete or partialelimination of the initial effects of anesthetics greatly contributes tothe well-being of a patient follow lng surgery.

Applicants vaporizer obviously has uses other than in the medical field.The embodiment illustrated is a highly eflici-ent vaporizer particularlyadapted for medical anesthesia purposes. It will be understood thatmodifications will be apparent to those skilled in the art, and it isintended that all such moditlcations within the spirit of this inventionare included within its scope, best defined by the appended claims.

We claim:

l. Apparatus for vaporizing liquids comprising, a container for liquidand a body member, said member having an inlet for gaseous fluids andbeing provided with at least one outlet, means extendible into saidcontainer for diffusing gaseous fluids through liquid in the container,means including a valve member, said member being movable relative tosaid body member to cooperate with said inlet and outlet to passportions of said gaseous fluids and dilused gaseous fluids to theoutlet, and pressure relief means including a spring adapted to exert apredetermined bias on said valve member, said bias being Sullicient toprovide a substantial gas seal between said valve member and said bodymember, but insufcient to prevent said valve member fro-m being raisedfrom its position relative to said body member to relieve any excessivepressures developing in said container.

2. Apparatus for vaporizing liquids comprising, a container for liquidand a body member, a pressure balancing means for uniform flow from saidcontainer including a chamber in said body member communicating withsaid container, said chamber having an inlet for gaseous fluids and anoutlet for delivering said gaseous fluids to said container, saidchamber being further provided with a second inlet for admittingvaporized liquids from said container for delivery to an outlet fromsaid chamber, means in said container communicating with said chamberfor diffusing gaseous iluids through liquid in said container, a valvemember within said chamber, said valve member being adapted forrotatable movement relative to said body member and being provided witha plurality of passages and grooves, means including a spring adapted toexert bias on said valve member, a plate member for sealing said chamberfrom the atmos phere, and means connected to said valve member andextending through said plate member for moving said valve memberrelative to said body member to selectively place said inlets andoutlets and said passages and grooves in various positions of registerfor passing portions of said gaseous fluids through liquid in thecontainer and by-passing other portions of said gaseous: fluids withoutcontact with the liquid, or by-passing all of said gaseous fluidswithout contact with liquid in the container.

3. Apparatus for vaporizing liquids comprising in com bination: acontainer for liquids; a control head mounted on said container; saidcontrol head having wall members defining a chamber therein, saidchamber having a bottom wall in covering relation with said container;means to secure said control head to said container; an inlet passageextending from the exterior of said container through a wall of saidchamber; an outlet passage extending through a wall of said chamber tothe exterior of said container; at least two container passagesextending from said chamber through said bottom wall to the interior ofsaid container; a tubular member connected to said control head inregistration with one of said container passages and extendingsubstantially to the bottom of said container; means mounted adjacentthe lower end of said tubular member for uniformly ditusing gaseous uids,from said tubular member into liquid in said container; a valve memberin said chamber, said valve member having passages therethrough andbeing selectively movable to connect said inlet passage to said outletpassage, said inlet passage to said outlet passage in combination withsaid inlet passage to the interior of said container and the interior ofsaid container to said outlet passage, and said inlet passage to theinterior of said container and the interior of said container to saidoutlet passage, said chamber being in communication with said containerthrough one of said valve passages in said last named connection,whereby a balanced pressure condition exists between said chamber andsaid container facilitating a uniform flow of vaporized liquid out fromsaid container; means to move said valve member to establish a selectedone of said connections; and pressure relief means for said containercomprising biasing means urging said valve member into covering relationwith said container passages, said biasing means yielding when apredetermined pressure within said container is exerted through saidcontainer passages against said valve member, said valve member movingout of covering relation with said container passages under the inuenceof pressure, permitting its release.

4. Apparatus for vaporizing liquids comprising in combination: acontainer for liquids; a control head mounted on said container; saidcontrol head having Wall members defining a chamber therein, saidchamber having a bottom wall in covering relation with said container;means to secure said control head to said container; an inlet passagefor gaseous fluids extending from the exterior of said container througha wall of said chamber; an outlet passage extending through a wall ofsaid chamber to the exterior of said container; at least two containerpassages extending from said chamber through said bottom wall to theinterior of said container; means in communication with said chamberthrough one of said container passages for diffusing gaseous fluids intoliquid in said container; a valve member in said chamber, said valvemember having passages therethrough and being selectively movable toconnect said inlet passage to said outlet passage, said inlet passage tothe interior of said container and the interior of said container tosaid chamber and said outlet passage, and said inlet passage to saidoutlet passage in combination with said inlet passage to the interior ofsaid container and the interior of said container to said outletpassage; means to move said valve member to establish a selected one ofsaid connections; and means including said valve member to relievepressure within said container, said pressure relief means beingautomatically responsive to the attainment of a predetermined pressurelevel within said container.

5. Apparatus for vaporizing liquids according to claim 4 in which thepressure relief means includes a coil spring which encircles a stubshaft projecting downward from the top wall of said chamber and analigned upwardly projecting shoulder portion of said valve member.

6. Apparatus for vaporizing liquids according to claim 4 in which thecontrol head is provided with an opening through an exterior wall toreceive liquids; a removable cap for said liquid opening, whereby saidcontainer may be replenished with liquid without removing the controlhead; a bleed passage through an exterior wall of said control head anda removable cover for said bleed passage, whereby pressure may be bledfrom the containers interior during a. liquid filling operation.

7. Apparatus for vaporizing liquids according to claim 4 in which saidvalve member has a tapered groove of progressively increasing volume,and said inlet passage terminates in a groove cooperating with saidtapered 8 groove to provide communication between said inlet passage andsaid container, said valve member being movable to register said groovesand arranged to provide a relatively wide variation in the degree ofregistration between said inlet passage groove and said Vtapered groove,the configuration of said tapered groove facilitating a relativelyprecise control over the quantity of gaseous fluid entering saidcontainer.

8. Apparatus for vaporizing liquid comprising a container for liquid anda control head, means for securing the head to the container, said headcontaining an inlet passage and an outlet passage terminating on theexterior of said container and at least two passages communicating withthe interior of said container, a valve body provided with a pair ofgrooves and pair of passages at least one of the passages communicatingwith one of said grooves, means communicating said pair of passages inthe valve body and a surface of the control head having a plurality ofpassages all communicating with the interior of said container, andpressure relief means for said container including means biasing saidValve body into contact with said control head surface having passages,said biasing means exerting a predetermined force against said valvebody adapted to provide a gas seal between said control head surface andsaid valve body but yielding when a predetermined pressure within thesaid container is exerted against said valve body, said valve body beingmanually movable in cooperation with said surface in one plane forselectively connecting: said inlet passage to said container and saidcontainer to said outlet passage; said inlet passage to said outletpassage; and said inlet passage to said container and said container tosaid outlet passage in cornbination with said inlet passage to saidoutlet passage; and automatically movable transversely in response to apredetermined pressure in said container to communicate all of saidpassages to the exterior of said control head.

9. In apparatus for vaporizing liquids to anesthetize patients, theapparatus being of the type having a container for liquid and a bodymember, said member having an inlet for gaseous fluids and another inletfor admitting vaporized liquids from said container and having at leastone outlet, a tube extending downward from the body member, said tubehaving diffusion means at its lower end, and means including saidinlets'and outlet and a valve cooperating with said body member forselectively passing portions of gaseous iluids through liquid in thecontainer and by-passing other portions of said gaseous uids withoutcontact with the liquid, or bypassing all of said gaseous uids withoutcontact with liquid in the container, the improvement comprising meansfor maintaining a uniform flow of vaporized liquid from said containerincluding wall means extending from the body member to define a chamberin communication with the container and the outlet, and pressure reliefmeans for the container including means exerting a predetermined bias tourge the valve against the body member in gas sealing relationship, saidbiasing means being adapted to yield under the influence of apredetermined pressure within said container permitting valve movementto relieve the pressure within the container.

References Cited in the le of this patent UNITED STATES PATENTS1,011,686 Westaway Dec. 12, 1911 1,191,700 Howes July 18, 1916 1,286,109Richardson Nov. 26, 1918 1,910,753 Colvin May 23, 1933 2,166,574Adolphsen July 18, 1939 2,223,456 Medsker Dec. 3, 1940 2,268,172 SinnettDec. 30, 1941 2,290,783 Turpin July 21, 1942 2,572,199 Richards Oct. 23,1951 2,902,269 Eichelman Sept. 1, 1959

